1. Field of the Invention
This disclosure is related to the field of hydraulic system filtration, in particular, to filter devices and apparatuses that are utilized to remove debris from automotive power steering fluid circulating through a power steering system.
2. Description of Related Art
Automotive power steering systems generally include a pump that circulates power steering fluid through the steering gear of a vehicle, a cooler, and back through the pump. In the process, debris, including small metal and ferrous particles from the metal surfaces of the power steering system, can be released into the power steering system. Thus, both metallic and non-metallic particles are often released into the system during use. Under the high pressure of the power steering system, the debris and metal particles form an abrasive-slurry. This abrasive-slurry can wear and/or damage the phenolic seals in the pump and steering rack. Further, this abrasive-slurry can travel via the power steering fluid throughout the entire steering system, causing wear and clogging various orifices and hoses, which can lead to expensive repairs. Accordingly, the debris and metallic particles and the damage they cause can be a major cause of power steering system failure.
Simply placing an internal filter in the power fluid steering system is insufficient to solve the problems caused by the presence of debris and ferrous particles in a power steering system. While these filter mechanisms can trap most of the non-metallic debris, they are generally unable to trap the minute ferrous metal particles which do most of the damage to the system since these particles are often small enough to pass through the filter. Further, installed internal filters can become clogged with debris which results in a failure of the flow of fluid within the system and catastrophically affects the operation of the vehicle's power steering.
One method currently utilized in the art to filter out debris and ferrous particles from a power steering system is a magnetic filter. A filtering element in these devices generally removes the larger non-metallic particles in the fluid. The magnetic ferrous components which are too small to be captured by the filtering element are generally removed by a magnet which is located at the return port of the pump.
An example of magnetic collection in conjunction with a filter device is provided in the “Self Dislodging Filter Element” of Stein, U.S. Pat. No. 7,704,384. While the filter of Stein is an advancement over traditional internal filters in that it is able to capture the smaller ferrous particles suspended in the power steering fluid, it still has inherent problems. First, the filter of Stein and similar filters of the prior art are generally self-dislodging which leads them to be easily removed from required location during installation and transportation, thus negating the ability to filter the fluid. Another problem with prior art magnetic internal filters like the filters disclosed in Stein arises from the placement of the magnetic element at the inlet port, with the mesh attached thereto. Problems with this orientation include contamination collecting on the magnet at the inlet port which restricts the overall flow of fluid within the power steering system, thus increasing the restriction as the metal contaminant is collected. In addition, the flow of the hydraulic fluid can dislodge contaminants attached to the magnet at the inlet port that are not contained by the mesh filter. Another problem is that the metallic contamination collects sludge and this sludge-like paste can attach to the magnet. This results in a higher detachment force required for the dislodging of the magnet for bypass. Further, in the event the mesh filter detaches from the magnet at the inlet port, both the floating mesh and the containments are a detriment to the pump in the power steering system. Even more problems associated with prior art magnetic internal filters like the filters disclosed in Stein include the following: a higher micron rating of the magnet which allows more contaminates to get into the pump; the orientation of the mesh bonded to the magnet inlet port creates a weak attachment which can result in separation of the mesh from the magnet inlet port and subsequent damage to the system when the pump uptakes the free floating mesh; and the fact that the filter has to dislodge to bypass.
Accordingly, there is a need in the art for a simple filter system and device that can filter out both debris and ferrous particles from a steering fluid system that is not at risk for inadvertent dislocation and separation of the mesh filter element.